[media] ivtv: Fix a sleep-in-atomic bug in snd_ivtv_pcm_hw_free

The driver may sleep under a spin lock, and the function call path is:
snd_ivtv_pcm_hw_free (acquire the lock by spin_lock_irqsave)
  vfree --> may sleep

To fix it, the "substream->runtime->dma_area" is passed to a temporary
value, and mark it NULL when holding the lock. The memory is freed by
vfree through the temporary value outside the lock holding.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
[hans.verkuil@cisco.com: removed unnecessary 'if (dma_area)']
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/pci/ivtv/ivtv-alsa-pcm.c b/drivers/media/pci/ivtv/ivtv-alsa-pcm.c
index 807ead20d212f559072e49673cdeb1c6492c8dcb..417d03da01f02dad76830ef66f57cff60cddd9c7 100644 (file)
--- a/drivers/media/pci/ivtv/ivtv-alsa-pcm.c
+++ b/drivers/media/pci/ivtv/ivtv-alsa-pcm.c
@@ -262,14 +262,16 @@ static int snd_ivtv_pcm_hw_free(struct snd_pcm_substream *substream)
 {
        struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
        unsigned long flags;
+       unsigned char *dma_area = NULL;
 
        spin_lock_irqsave(&itvsc->slock, flags);
        if (substream->runtime->dma_area) {
                dprintk("freeing pcm capture region\n");
-               vfree(substream->runtime->dma_area);
+               dma_area = substream->runtime->dma_area;
                substream->runtime->dma_area = NULL;
        }
        spin_unlock_irqrestore(&itvsc->slock, flags);
+       vfree(dma_area);
 
        return 0;
 }